April,

My middle finger is too fat for a standard thimble, but the Barb T. pattern works wonderfully well!

I develop a callus on the side of my left index finger (which is backing the pleat which I sew) from being lightly stabbed by my needle as I stitch. It's not more prominent than you might acquire from moderate gardening chores; but if your skin is tender, then try to avoid using the finger as your stitch gauge! Perhaps you'll be more adept than I: my prior experience is bachelor level hand work and a little light machine sewing.

Work on the pleating posture as described, and do whatever you need to do to accommodate the stretching + stitching operation.

I promise that you'll have fun!